In the U.S., alcohol liver disease (ALD) affects more than 10 million people and accounts for 48% of liver cirrhosis-associated deaths. Currently, the only effective treatment option for alcohol-induced liver cirrhosis and cancer is liver transplantation. Therefore, it is imperative to develop new therapeutic strategies. Alcohol-induced endotoxemia is a critical factor in causing ALD. Accumulating data demonstrate that excess ethanol intake induces endotoxemia through two main mechanisms: 1) stimulation of bacterial overgrowth and 2) disruption of gut mucosal barrier dysfunction. Our preliminary studies demonstrate that lactoferrin (LF) suppresses alcohol-induced gut hyper-permeability. We will examine the hypotheses that lactoferrin can maintain the balance of gut microbiota and preserve the integrity of the intestines despite alcohol consumption, and as a result, lactoferrin prevents the transfer of endotoxin to the portal vein, reduces endotoxemia, and attenuates ALD. The Specific Aims of the proposed studies are: (Aim 1) Determine whether LF attenuates ALD by reducing alcohol-induced gut leakage and endotoxemia. Female C57Bl/6J mice will be divided into several groups and treated with: i) Liber-DeCarli control liquid diet, ii) alcohol-containing liquid diet, iii) LF (50 mg/kg), iv) alcohol plus various doses of LF. We will examine whether a) oral administration of LF prevents endotoxin transfer from the gut to the portal vein and decreases alcohol-induced hepatic inflammation and injury; and b) the protective effects of LF on gut barrier function are due to LF-induced gut epithelial cell growth/migration and/or suppression of the inflammatory response of epithelial cells to LPS stimulation. (Aim 2). Determine whether LF attenuates alcohol-induced enteric dysbiosis. This aim will profile and compare enteric microbiomes in 4 groups of mice treated with i) Liber-DeCarli control liquid diet, ii) alcohol-containing liquid diet, iii) LF, iv) alcohol plus LF. We will investigate whether a) alohol treatment increases the prevalence and/or abundance of pro-inflammatory enteric microbes (e.g., Gram-negative endotoxin producing bacteria) and reduces the occurrence of anti-inflammatory microbes (e.g., lactobacilli, bifidobacteria); and b) oral administration of LF restores the normal enteric microbiome. (Aim 3). Identify microbial and host gene-expression networks that differ following alcohol and alcohol plus LF administration. Microbial and host transcriptomes will be profiled in order to determine how alcohol and/or LF alter the metabolic networks operating in the enteric mucosa. We will determine whether a) oral administration of alcohol induces gene expression profiles in 1) metabolic networks of enteric microbes that produce pathogenic products of alcohol metabolism and 2) host intestines that are indicative of gut barrier dysfunction. We will also examine whether oral administration of LF ameliorates alcohol-induced changes in microbial and host enteric gene expression profiles.